# COSMO360 · Stellar atlas

Star coordinates, spectral classes, apparent magnitudes, colour indices, luminosities and distances: [HYG v4.1](https://github.com/astronexus/HYG-Database/tree/main/hyg), David Nash / Astronexus, derived from Hipparcos, Yale Bright Star and Gliese catalogues. [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/). The adapted stellar catalogue is distributed under the same licence. RA/declination use J2000. Parsecs are converted to light-years with 3.26156. HYG distance >=100000 is a missing/dubious-parallax sentinel and is displayed as unknown, never a measured distance. This catalogue snapshot is not a claim of the latest distance estimate; measurement uncertainties are not included.

All 88 constellation names, centres and conventional line figures: [D3-Celestial](https://github.com/ofrohn/d3-celestial), Olaf Frohn, BSD 3-Clause; full licence alongside this file. Serpens Caput and Cauda are combined into one official constellation. Lines are conventional guide figures, not official IAU boundaries, physical bonds or 3D distances.

Official constellation system: [IAU](https://www.iau.org/IAU/IAU/Astronomy-FAQs/Constellations.aspx) and [NASA StarChild](https://starchild.gsfc.nasa.gov/docs/StarChild/questions/88constellations.html). Authored Russian descriptions explain the figures, not measured physical associations.

Selection includes HYG stars with apparent visual magnitude <=6.5 plus named stars. The night-sky view places them on a celestial sphere by angular coordinates; physical depth view uses their catalogue distances, where available.

Real photographs: [ESO image archive](https://www.eso.org/public/images/), [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). See [the photographic archive sources](photos/SOURCES.md) for full per-image credits, fields, bands and adaptations. A curated selection covers 14 constellations, not all 88.